We have used the methods of behavioral neurophysiology to study six major divisions of the frontal lobe of primates: the dorsal premotor cortex (PMd), the ventral premotor cortex (PMv), the frontal eye field (FEF), and the supplementary eye field (SEF), the supplementary motor area (SMA), and the prefrontal cortex (PF). There has long been a need for more powerful behavioral methods with which to distinguish neuronal activity related to sensory and perceptual processes from those involved in the selection and control of behavior and to distinguish the activity in functionally distinct, but functionally related cortical fields. We have developed three novel behavioral paradigms that distinguish sensory from motor activity in frontal cortical neurons. Our results support the hypothesis that PMd plays a role in retrieving from memory the movement that needs to be made on the basis of a sensory event, but that PF is more involved in spatial analysis and other aspects of sensory information processing. Further, FEF and SEF cells modulate their activity during non-spatially instructed as well as during spatially instructed oculomotor tasks. This finding emphasized the similarities between the frontal skeletomotor and oculomotor fields.